Massachusetts Democratic Sen. Elizabeth Warren indicated that her race was “American Indian” in a handwritten registration form filed in 1986 with the Texas State Bar, according to a new report on Tuesday that documents the presidential hopeful’s efforts to identify as a minority during her earliest days as a law professor.

The revelation, initially reported by The Washington Post, is the first known instance of Warren claiming Native American ancestry in an official document or in her own handwriting. It threatened to add more ammunition to already-frequent attacks by Republicans, including President Trump, deriding Warren for claiming such ancestry to bolster her academic career.

Warren’s office, questioned by The Post, did not dispute the authenticity of the bar card.

Last week, Warren apologized to the Cherokee Nation for taking a DNA test in an attempt to prove she had Native-American ancestry, and on Tuesday, she again more broadly apologized for identifying as Native American “for almost two decades,” according to The Post.

“For the seven years this has been in the news, Elizabeth Warren has refused to apologize. Now, four days before her formal presidential launch, she’s issued a politically opportunistic apology that doesn’t go nearly far enough,” Republican National Committee (RNC) spokesman Mike Reed said in a statement, referring to Warren’s plan to formally begin her campaign for the White House on Saturday. “Warren pretended to be a minority to climb the Ivy League ladder – a lie that will continue to haunt her presidential ambitions.”

The bright-yellow bar card is dated April 1986, when Warren was a professor at the University of Texas School of Law. Past reporting by several outlets, including CNN, had indicated that Warren “had not” listed herself as a minority in her “student applications and during her time as a teacher at the University of Texas.” Records unearthed by The Boston Globe found that in 1981, 1985, and 1988, personnel forms at the University of Texas showed that Warren had called herself “white.”

Here is the form Elizabeth Warren filled out for the State Bar of Texas claiming American Indian heritage. pic.twitter.com/VwHifS7BCL

The State Bar document, which functions as a kind of directory entry for lawyers, is among multiple instances in which Warren described herself as a Native American. She indicated that she was Cherokee in an Oklahoma cookbook called ” Pow Wow Chow” in 1984, and listed herself as a minority in the Association of American Law Schools Directory of Faculty from 1986 to 1995 — a move she said later was an effort to “connect” with other “people like me.”

Warren dropped off the list in 1995, after moving to Harvard Law School. But in 1996, an article in the student-run Harvard Crimson apparently indicated that faculty members and administrators still believed Warren was Native American.